Jimmy127 posted on XDA how to root your Atrix 2 [HOWTO] Root the Atrix 2 - xda-developers

I didn't want to repost it; but it seems to be working.

There are also some ways to unlock the service check on the tethering app so you can tether for free. I tried both successfully and then did a system wipe (still in the warrenty period might return it for something better).